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The performance of an internal permanent magnet MISC machine (IPMMM) is improved by its cylindrical rotor, which dampens torque ripple. Changing the stator and rotor core materials, comparing with torque values to identify efficient motor and keeping that in consent, then change the magnet material for better ripple torque. The change in the rotor materials to vary the torque by the rotor angle is analyzed. The finite element method is applied to a MISC motor operating at 290 V, 20 A, and 3000 r/min with the goals of increasing torque and decreasing torque ripple. In this machine, changing stator and rotor materials improves the torque. The results are calculated and analyzed numerically, with the results being virtualized graphically. [ABSTRACT FROM AUTHOR]

The size of magnetic components can be reduced with novel designs, but the intricate structures are difficult to make due to the limited sets of conventional magnetic core geometries and materials. Magnetic pastes have the flexibility of forming complicated structures with a pressure-less and low-temperature molding process, and are ideal for making the novel magnetic designs. The conventional approach of developing magnetic pastes involves time-consuming experimental iterations to determine the optimal composition parameters. Instead of relying on the trial-and-error efforts, we explored a computer-aided approach to guiding the magnetic paste development by creating material’s microstructure by discrete element method (DEM) and studying the property by finite element method (FEM). From a starting formula with two different-sized spherical powders, we improved the composition guided by DEM and FEM, and studied the magnetic permeability versus two variables: powder mixing ratio and magnetic volume fraction. The simulated permeability agreed well with the experimental data with an average error of only 10%. With the computer-aided formulation methodology demonstrated in this work, one can develop magnetic pastes with minimum experimental efforts and explore different compositions to meet various magnetic design needs. [ABSTRACT FROM AUTHOR]

This article presents the rotor optimization in an interior permanent magnet synchronous machine (IPMSM) with high-strength non-grain-oriented (NGO) silicon steel material. Different from simple replacement with high-strength NGO, this article presents a customized design to make the best use of rotor iron core material. Specific optimization of the rotor topology is presented, followed with simulation verification by finite element method (FEM). Based on the simulation results, the benefits and limitations of the optimization design with the replacement of high-strength NGO are listed. In order to further overcome the limitations of the presented optimization design, magnetic characteristics of the high-strength NGO laminations subjected to various tensile stresses are measured in the experiment. Finally, experimental results are analyzed, and the conclusions to employ high-strength NGO for IPMSM are summarized. [ABSTRACT FROM AUTHOR]

The residual flux measurement is one of the difficulties in the transformer research field. This article presents a residual flux density (${B} _{\mathrm {r}}$) measurement method considering the relative differential permeability ($\mu _{\mathrm {rd}}$) of the core material. First, the basic relationship between $\mu _{\mathrm {rd}}$ and ${B} _{\mathrm {r}}$ is analyzed on the basis of the magnetic domain theory. Then, combining the experimentally measured relationship between ${B} _{\mathrm {r}}$ and $\mu _{\mathrm {rd}}$ , using $\mu _{\mathrm {rd}}$ as an intermediate variable, the relationship between ${B} _{\mathrm {r}}$ and time constant is derived. Furthermore, a square iron core model is established by the finite-element method, and the empirical formula for calculating ${B} _{\mathrm {r}}$ is was fit. Finally, the feasibility of this method and the accuracy of the proposed empirical formula are verified through experiments. [ABSTRACT FROM AUTHOR]

Fringing losses play a detrimental role in high-frequency transformers. The tendency toward higher power density and miniaturization of power converters leads to higher switching frequency and enforces the use of low-profile components such as gapped planar transformers. Due to the air gap, lower magnetizing inductance and better regulation of LLC (Lm, L2, Cs) can be achieved, but fringing fluxes can also be induced, resulting in extra magnetic losses and more hotspots. These losses are highly dependent on the frequency and the core material, so it is critical to model them for gapped planar transformers in LLC resonant converters, which operate at high frequencies and use ferrite material. In this article, fringing losses for gapped ferrite transformers in LLC converters are thoroughly modeled in order to provide a precise prediction regardless of the materials and core geometries. The proposed method provides an accurate and compact formula for predicting the fringing losses of planar transformers. This formula is obtained based on the finite-element method so as to consider and evaluate different design parameters. An LLC resonant converter with different planar transformers is implemented to show the compatibility of the proposed model. Experimental results show the higher accuracy of the proposed model compared to traditional ones and confirm that the proposed loss model can be applied to diverse core shapes. In addition, the gradient descent method is used to calibrate the theoretical and experimental results. Moreover, temperature deviations of the transformer due to the fringing losses are measured and evaluated both experimentally and theoretically to show the accuracy of the proposed loss formula. Due to the proposed model's higher accuracy, an improved design procedure for planar transformers is obtained, adding substantial value for design engineers. [ABSTRACT FROM AUTHOR]

This article describes a method to calculate iron loss of permanent-magnet machines by considering the hysteresis loops affected by multi-axial stress. A simple hysteresis model is introduced and modified by reluctivity and hysteresis loss increase ratios, which can be determined by core material experiments under uniaxial stress. This model is coupled with time-stepping finite-element analysis. The validity of the proposed method is confirmed by the core material experiments under multi-axial stress and measured characteristics of permanent-magnet machines. It is clarified that the accuracy of the proposed method is acceptable. [ABSTRACT FROM AUTHOR]

We have investigated the effect of magnetic saturation of core materials on the diagnosis of static and mixed-eccentricity faults in induction motors. We modeled the faults by using a modified winding function (MWF) and time-stepping finite-element (TSFE) methods to compute the stator currents of both healthy and faulty motors for processing. We then analyzed the stator signal spectra of the motors by the MWF and TSFE methods and estimated the amplitudes of sideband components attributable to the faults. The results obtained by TSFE agreed well with experimental measurements. However, there was considerable discrepancy between the MWF results and the experimental measurements. We investigated the reason for the discrepancy by analyzing the air gap magnetic field distribution in both healthy and faulty induction motors in order to determine their linear and actual magnetization characteristics. We found that, in a faulty motor, for fixed permeability, the analytic method yields a much larger magnetic flux amplitude than is actually the case. At the same time, the distribution of magnetic flux in the air gap is more asymmetric than the actual case. Here, we present our experimental results and those obtained with the MWF method, using the finite-element analysis package Opera2d 10.5, for two three-phase, four-pole, 60-Hz, 3-hp motors having 36 stator slots and 44 and 28 rotor slots, respectively. [ABSTRACT FROM AUTHOR]

Application of fine-grained doubly oriented electrical steel sheets that have a strong {100}(001) texture to synchronous interior permanent magnet motors has been investigated. The alteration in stator core material from high grade nonoriented electrical steel sheets to the doubly oriented material with a simple change in stator design was found to lead to an increase in efficiency up to more than 2%. This efficiency increase is ascribed to a larger permeability and a lower iron loss in two perpendicular directions of the doubly oriented material. Finite-element analysis has revealed that the magnetic field distribution in stator cores made of the doubly oriented material is largely different from that in stator cores made of the nonoriented material. [ABSTRACT FROM AUTHOR]

This paper presents the results of two-dimensional (2-D) finite-element analysis (FEA) carried out on 8/6 and 6/4 doubly salient permanent magnet (DSPM) motors to arrive at the magnet leakage factor and the flux density ratios of various parts of the motors so as to aid the designers of this newer motor. The two permanent magnets being kept embedded in the stator halves along with the typical doubly salient structure of the DSPM motor causes more leakage of the magnet flux. After extensive FEAs of the two configurations of the motors, it is observed that a magnet leakage factor of 132 is giving the correct results for use in conventional designs of this motor. Based on the optimum designs of the two motors, the flux densities in the airgap, rotor yoke, rotor pole, and stator yoke can be 1, 0.5, 0.9, and 0.5 times the flux density considered for the stator pole, which will normally be just above the knee-point value of the B-H characteristics of the core material used. [ABSTRACT FROM AUTHOR]